looks like a raccoon but daytime like a hawk

Hi, first thank you all for your time... I've read the Predator Identifier sticky but I'm still confused.
Though the two incidence may be unconnected, I'll start from the beginning. (Sorry it's so long).
We have a stall - rubber mats on concrete floors, met by wooden walls. This is where our chickens lived. There has pretty much always been some obvious activity of rats, including burrows from the wall-floor joint. We haven't done anything about it because nothing is really level, there are gaps in many places, and they can clearly find a way - considering the wood doesn't have much to do with it... they're coming from under the concrete.
Anyway, every night, just as it's getting dark, my boyfriend or myself go out and shut the chickens back in their stall (they've been out on a big field all day, there is tonnes of thick brush that I thought would keep them safe (and it did for nearly two months). So one night, two days ago, my boyfriend intended to but did not shut the door behind the chickens (they round themselves up and are always waiting there for us to close the door for the night and turn of the light).
So in the morning I go out and could only find two of them, Zelda and Mononoke. They followed me to the stall where I fed them and then had to leave for work. I left the stall open because it was day time and I was hoping the rest of them would come back. So when I get off work at 6, my boyfriend has been home and said he has Mononoke and two others... Zeldas body is in the field. So, our first casualty is outside, in the daylight ( I saw her that morning). Her head and neck is all chewed up and that's pretty much it.
Not knowing how related the rat issue in the stall is, I did the best that I could to make our three remaining ladies as safe as I could - I brought my bunnies inside and put the chickens in their hutch. At this point it is again dark and worth noting the chickens were already bunkered down VERY close to the bunny hutch, one on top. The hutch is right outside of their own stall. Clearly they did not feel safe in there. On top of that, I scooped them each up and they let me, without struggle. They were terrified of something and let me help them.
So if your chicken-expierenced brains don't already have gears turning I'll let you know what I've come up with so far - I believe that the night we left the door open is the night they felt they could finally escape the rats. I feel horrible that they felt so unsafe in their own home, probably every night since I got them. (Come to think of it, they are about 2 weeks past when they should have been laying... we now believe they have been laying but the rats have been getting to it before us. ) So - I think they were frightened at night and took off, probably in a flurry and became scattered (we found the survivors and the bodies all over the field.) I think this drew the attention of a sleepy hawk who kept an eye on it until afternoon and then killed Zelda (I saw a big hawk flying around that morning). Except (here's where I get confused)... her head and neck was gone as if it was a raccoon (licking the blood up from the arteries I hear...) but it was day time and racoons don't hunt in daytime... was this an odd occasion where one did... was it the hawk, or did the rats do it... (a good 30 feet from the stable).
So our solution so far is to build a hutch like the rabbits, because clearly the rats have been stressing them out, and bringing both hutches away from the stable and to the house, where we have a cat who does a pretty darn good job.
If you can explain this day time death (another was found dead, but it was over a day and night and nothing was left to tell if it was the final hen or our only (young) rooster. The other, whoever wasn't the body must be dead somewhere or maybe will still come back,) I would be very grateful... like I said, I'm going to have them in a hutch from now on (got to build one today so the bunnies can have theirs back,) but I would really just like some closure...

 

Thanks for the reply, I know I really babbled on!
I've read on these threads the threat of animals pulling their heads through bars, but the hen whose head I saw eat was in broad daylight, in the middle of a field (just out of the cover of some bushes). Thank you for your input, I'm sure the rats had a go at her for sure Unless the hawk who killed her did it herself... I don't know if hawks eat... their heads.